Neonatal health is dependent on early risk stratification, diagnosis, and timely management of many potentially devastating conditions. Preterm infants are at increased risk of prematurity-related complications, including: early-onset sepsis, chronic lung disease, intraventricular hemorrhage, necrotizing enterocolitis, and neurodevelopmental impairment.Many of these conditions are poorly predicted in real-time by clinical data, including currently available diagnostic testing. Thus, biomarkers have been sought to aid early and targeted treatment and prognosis for these conditions. Umbilical cord blood may represent a novel source of molecular signatures that provides a window into the state of the fetus at birth. Umbilical cord blood inflammatory markers have been studied as diagnostic indicators of early-onset sepsis. Specific cord blood cytokines have been studied as predictors or correlates of retinopathy of prematurity, atopic disease, infantile hemangioma, placental histopathology, and more. However, few of these cord blood biomarkers have been translated into diagnostic tools in clinical practice. Longitudinal profiling of postnatal proteomic changes has provided insights into the development of the immune system over the first weeks to months of life. While proteomic profiling of cord blood has demonstrated immunologic differences between preterm and term infants, prior research has lacked inclusion of preterm infants across the continuum of gestational age and consideration of key perinatal characteristics such as the route of delivery, preeclampsia, intraamniotic infection, and neonatal sepsis that are likely to affect protein expression. In this study, we have comprehensively characterized the cord blood proteome from infants born between 25 to 42 weeks using MS to provide a benchmark of normative cord blood proteomic profile and examine proteome differences across the developmental range of gestational ages.